BUG: Fixed a bug in ExpectationMaximiationMixtureModelEstimator.

Because of the bug, the parameters of some Gaussian components are not updated
once the previous components has change. The UpdateParameter function stops
early. After fixing it, the example on the Wiki page works.

Change-Id: Id9701af09722b7c90f37cd8f82a38293b54185d3
ENH: Expose the output stream operator for LightObject

Change-Id: Ibfe930b6b005eb7811324a203b83c08c5c2d9287
Merge topic 'release-FixExpectationMaximizationFilter'

6b23ae6b BUG: Fixed a bug in ExpectationMaximiationMixtureModelEstimator.
Merge topic 'expose-lightobject-stream-operator'

b57f19a8 ENH: Expose the output stream operator for LightObject